Investigation of mRNA expression of tumor necrosis factor-alpha, interleukin-1beta, and cyclooxygenase-2 in cultured equine digital artery smooth muscle cells after exposure to endotoxin.

This research article investigates the impact of endotoxin exposure on the mRNA expression of inflammatory markers such as COX-2, TNF-alpha, and IL-1beta in equine muscle cells. The findings suggest that COX-2 mRNA expression in vascular smooth muscle cells may have a significant role in instigating endotoxemia in horses, which could lead to other conditions like laminitis.

Objective

The main objective of this research was to determine the mRNA expression of cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-alpha, and interleukin- (IL)-1beta in cultured equine smooth muscle cells after exposure to endotoxins.

Methodology

• The palmar digital arteries were collected from six clinically normal adult horses.
• Explants from the tunica media of these arteries were used to cultivate primary smooth muscle cells (SMC).
• Equine mononuclear cells were used as control cells.
• The vascular SMCs and control cells were then exposed to lipopolysaccharide, an endotoxin (at 20 microg/ml and 100 ng/ml respectively).
• Following exposure, a Northern blot analysis with equine-specific probes for COX-2, TNF-alpha, and IL-1beta was performed on the isolated total cellular RNA.

Results

• The results showed no message for IL-1beta or TNF-alpha in either control or endotoxin-exposed equine vascular SMC from all horses.
• However, there was a distinct and notable uptick in COX-2 regulation after endotoxin exposure.
• Furthermore, endotoxin-exposed equine mononuclear cells showed an upsurge in the regulation of IL-1beta and TNF-alpha mRNA.

Conclusion

The increase in COX-2 mRNA expression by equine vascular SMC is likely a critical early pathophysiologic event in the onset of endotoxemia in horses. The amplified local vascular production of various prostanoids as a result of increased mRNA expression for COX-2 may lead to vasoactive events witnessed in occurrences of laminitis. This newfound understanding could aid in further elucidating the diseases’ pathogenesis and guide the development of new therapeutic strategies.